This invention relates to a magnetic actuator for producing mechanical movement in a pump or other output means.
Heretofore, there have been a number of magnetic actuators which operate on the basic principle of changing the polarity of a magnet. Typical examples of this are found in U.S. Pat. Nos. 2,198,506; 2,568,757; 3,320,894; 3,384,021; 3,488,614; 3,492,819; 3,606,595 and 3,878,412.
It is a known practice to change the polarity of a magnet in order to produce reciprocating movement. This is done by placing a movable magnet between two stationary magnets and changing the polarities of the magnets so that the movable magnet travels first toward one stationary magnet and then toward the other stationary magnet in a shuttle-like fashion. Such an arrangement imposes constraints on the distance which may be traveled by the driven magnet, inasmuch as the air gap between it and the stationary magnets must be minimized in order to deliver a useful amount of force to the output means.
According to this invention, a plurality of magnets are arranged along an axis so that there are air gaps between the adjacent magnets. Means are provided for changing the polarity of one of each adjacent pair of magnets to move adjacent magnets between mutually proximate relative positions where the air gap therebetween is substantially closed and mutually distant relative positions where the air gap is open. With such an arrangement, some of the magnets will move through a distance which is greater than the thickness of an air gap, thus producing a maximum stroke while at the same time delivering a useful amount of force to the output means. In accomplishing this purpose, stop means are preferably provided to limit the extent of movement of magnets away from each other when they are in their repelling polarity conditions.
For a more complete understanding of the invention, reference is made to the following description and to the accompanying drawings.